What is "Bonam Partem" ? The word "Bonam Partem" means that words used in the ststute are to be taken in their lawful sense.

What is "Lawful Sense" ? The word " Lawful Sense" implies what is legitimate and recognised by the law.

Conclusion:-Therefore , it involves lawful discharge of duities.

IT Act,1961-An Exception To Above Rule :- There is an exception to above rule. This refers to illegal profits which are subject to income tax asessment.

In my opinion ,that is why the term "Income "has been defined in an "Inclusive Manner"under the IT Act,1961, so as to include within its ambit  certain items which would have otherwise fallen outside its scope. 

Conclusion:- If illegal profits are not subject to Income Tax(IT) , the purpose of  IT Act,1961, wil be defeated and the profiteers are allowed to escape the liabilityto payment of tax by seting theirs own wrongs. Hence , in my opinion, above exception appears to be good and reasonable.